Dissertation
Dissertation > Medicine, health > Internal Medicine > Infectious disease > Fungi and actinomycetes infectious diseases

The Study on Association of Cytokine Polymorphism of Immunity with Invasive Fungal Infection in Hematological Patients

Author MaoYuJing
Tutor SunJing
School Southern Medical University,
Course Internal Medicine
Keywords hematologic disease Invasive fungal infection cytokine Genetic polymorphisms
CLC R519
Type Master's thesis
Year 2011
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BACKGROUND & OBJECTIVEInvasive fungal infection(IFI) is a common and life-threatening infection in hematological patiens,specially in allogeneic haematopoietic stem cell transplant (allo-HSCT)recipients,which is difficult in diagnosis and has a high mortality.In the last decades, modern and sophisticated medical care has made a reality that more patients choose to accept stem cell transplantation,especially as the progress of unrelated-donor、HLA—unmatched donor and haploidentical transplantation.This has greatly improved the prognosis of hematologic patients.However,such advances have also resulted in an increased risk for invasive fungal. Despite presenting similar degrees of immunosuppression, not all individuals at-risk ultimately develop fungal diseases,this involves the study of the host genetic backgroud and its relationship to fungal disease.It is now clear that host genetic factors play a major role in determining differential susceptibility to infectious diseases of humans, and its own defense mechanisms determine the response to the infectious challenge and the ensuing pathology.Host genetics play a key role in elucidating susceptibility and tolerance to disease or poison,diversity of clinical manifestations of disease and responsiveness to drug therapy. Research on gene polymorphism can reveal the nature of bioactive substances and functional differences in different individuals from the gene level. As an opportunistic infection with different clinical manifestations and pathological findings,IFI could be a good explanation of host genetics.Cytokines is important in the anti-fungal immunity. Thl-produced cytokines (including IFN-γ, IL-6, IL-12, TNF-α, IL-1)activate neutrophils and pulmonary macrophages, the key effector cells in invasive aspergillosis, whereas Th2 cytokines, notably IL-4 and IL-10, are associated with worse disease progression,more tissue damage and poor prognosis.Cytokines are produced by activated immune cells(including lymphocytes and non-lymphocytes)and some stromal cells.Cytokines are signaling molecules that mediate cell proliferation,differentiation,generating functions and maintaining cell survival.Cytokine synthesis,secretion and biological effects are all regulated by cytokines gene. Individual differences in cytokine synthesis are of large,some may be a difference of more than 10 times.Difference is mainly due to the variation of cytokine genotypes and gene regulatory region or promoter region polymorphism.Some foreign scholars have carried out some studies on innate immunity genetics that associates with susceptibility to fungal diseases,and found that some of the major components of innate immunity are of great relevance with susceptibility to IFI,such as TLR4 Asp299Gly、Thr399Ile, TLR1 Arg80Thr, TLR6 Asn248Ser, Ser249Pro; MBL low—yielding haplotype (HYPD haplotype for example), MASP2 Asq472Asn; IL-15+13689A/T, TNF-a-308G/A, IFN-γ+874T/A, CXCL1011101C/T、1642C/G、-1101A/G and so on.However,there is no TLR4 Asp299Gly、Thr399Ile polymorphisms were found in Chinese population so far. And in Chinese population 54 sites point mutation is main polymorphism in the first exon of MBL2. Someone reported that MBL54G/A mutation frequency in Guangdong Han population is 0.057%. While the mutation frequency of some cytokines are very high, Someone reported that TNF-α-308 site mutation freuency is 0.057 and IFN-γ+874 site mutation freuency is 0.293 in Guangdong Han population. So we only select to study these high-mutation freuency gene in the Chinese population to investigate the relationship between gene polymorphism and IFI susceptibility.There is not yet research in this area in our country at present. Occurrence of a distinct Gene polymorphism within a population primarily depends on the geographical or ethnic group, which is studied. Foreign genetic variation of immune is not necessarily suitable for the status of our contry.Therefore,it is significant to study gene polymorphism associated with susceptibility to IFI. In this review, we will discuss the genetic variables of the immune system contributing to susceptibility to fungal diseases by studying on cytokine polymorphism.We hope to achieve IFI risk stratification forecast in patients with immune suppression,especially in patients with hematologic malignancies,and provide the basis for layering host factors in IFI diagnosis criteria and for investigating individual prevention and treatment strategies.Method一、The occurrence of IFI in patients after allo-HSCT in southern hospital1.Case Information:163 cases received allo-HSCT between August 2008 and November 2010. Among them there are 102 cases meet the criteria, and all received long or short course of itraconazole as anti-fungal primary prophylaxis.And 48 cases were divided into long course group and 54 cases into short course group. Transplantation Regimen:use conventional chemoradiation therapy and the immunosuppressive agents for prophylaxis and treat-ment of graft-versus-host disease and agents to prevent and treat bacterial and viral infections. Follow-up study to 2010-12-31, the median follow-up time is 298.5 days. 2.Statistical analysis:using descriptive analysis for the characteristics of IFI, pearson chi-square test for non-continuous variables, two samples T test for quantitative variables. Application SPSS 17.0 software for statistical analysis.二、The genetic factors influnced the development of IFI in hamatological patients1 Case Information:53 cases with hematologic diseases from Nanfang Hospital,which received at least two courses of cytotoxic therapy or received allogeneic haematopoietic stem cell transplantation and developed invasive fungal infecion(diagnosis or clinical diagnosis,mostly from southern China) were screened.And of these,16 patients received allo-HSCT. They were all registerd a complete medical history data,with long-term follow-up conditions.65 cases healthy normal people as the control group.2 blood collection:collect 2ml peripheral blood of patients or healthy controls,-20 degrees save.3 SNP analysis of immune response genes for IFI-positive patients and healthy controls:Polymerase chain reaction-restriction enzymes method (PCR-RFLP) analysis of TNF-α-308G/A, TGFβ1+869C/T polymorphism; Polymerase chain reaction with sequence specific primers (PCR-SSP) analysis of IFN-y+874T/A polymorphism.4 Statistical analysis:descriptive analysis for the gene mutation analysis; Pearson chi-square test for comparation gene frequencies and genotype distribution and allele IFI occurrence rate differences, application SPSS 17.0 software for statistical analysis.Result1, IFI incidence and characteristic.The overall survival (OS) of 102 allo-HSCT patients who received itraconazole as anti-fungal primary prophylaxis in our hospital were respectively 89.8%、83.2% and 76.8% when 90days.180days、12 month after transplantation.The occurrence of invasive fungal infection (IFI):The incidence rates of IFI in 102 patients were respectively 7.84%、9.80%、10.78% and 24.51%when 30days、90days、180days、12 month after transplantation,consistent with date reported in other literature. The incidence rates of invasive fungal infection in long and short group were respectively 8.3% and 7.4%; 10.4% and 9.3%; 10.4% and 11.2%; 10.4% and 21.4% when 30days.90days、180days、12months after transplantation,without significant difference(P=0.643).And there was no without significant differenc in survival of the two groups(P>0.05).2,TNF-α-308, TGFβ1+869, IFN-γ+874 genotype distribution frequencyIFI-positive group and healthy control group:TNF-α-308 site of GG and non-GG genotypes in the IFI positive group were 71.7%、28.3%; in healthy control group were 44.6%、45.4%. Between the two groups GG genotype frequency was significantly different (χ2= 8.726, P=0.003). TGFβ1+869 site of CC and non-CC genotypes in the IFI positive group were 45.3%、54.7%; in healthy control group were 21.54%、78.46%. Between the two groups CC genotype frequency was significantly different (χ2= 7.539, P=0.006). IFN-γ+874 site of TT and non-TT genotypes in the IFI positive group were 32.1%、67.9%; in healthy control group were 21.54%、78.46%. Between the two groups TT genotype frequency was significantly different (χ2= 5.647, P=0.017)3, TNF-α-308G/A, TGFβ1+869T/C, IFN-γ+874 genotype and the occurrence of IFI.3.1 TNF-α-308G/A and the occurrence of IFI:①TNFα-308 genotype and the occurrence of IFI:TNFα-308 genotype was statistically significant (P= 0.003). Compare to the GG-type, none-GG genotypes (GA,AA) is the protect factor of the occurence of IFI (OR=0.318,95%CI=0.147-0.688)②TNF-a-308 allele and the occurrence of IFI:Carrying A allele has less risk than carrying G allele, the difference was significant (χ2=9.279, P=0.002).Carrying A allele was a protect factor (OR=0.386,95%CI=0.207-0.720).3.2 TGFβ1+869 C/T and the occurrence of IFI:①TGFβ1+869 genotype and the occurrence of IFI:TGFβ1+869 genotype was statistically significant (P= 0.003). Compare to the CC-type, none-CC genotypes (CT,TT) is the protect factor of the occurence of IFI (OR=0.302,95%CI=0.134-0.681)②TGFβ1+869 allele and the occurrence of IFI:Carrying T allele has less risk than carrying C allele, the difference was significant (χ2= 5.259, P=0.022).Carrying T allele was a protect factor (OR=0.545, 95% CI=0.324-0.918)3.3 IFN-γ+874T/A and the occurrence of IFI:①IFN-γ+874 genotype was statistically significant (P= 0.017). Compare to the none-TT type(TA,AA), TT genotypes is the risk factor of the occurence of IFI (OR=2.938,95%CI=1.183-7.300)②IFN-γ+874 allele and the occurrence of IFI:Carrying T or A allele has no relationship with the occurrence of IFI. the difference was not significant (χ2=3.328, P=0.068)Conclusion1, The incidence rates of invasive fungal infection and survival rate after transplantation in long and short group have no significant difference(P=0.643). And there was no without significant differenc in survival of the two groups.1, TNF-α-308, TGFβ1+869 and IFN-y+874 genotype frequency distribution were different between IFI-positive group and healthy control group.2, TNF-α-308G/A polymorphism correlate with the occurrence of IFI: compare to GG-type, none GG type is the protect factor of the occurrence of IFI, Carrying A allele was a protect factor.3, TGFβ1+869 polymorphism correlate with the occurrence of IFI:Compare to the CC type, none CC-type is the protective factor of the occurrence of IFI. carrying T allele was a protective factor.4, IFN-γ+874 polymorphism correlate with the occurrence of IFI:Compare to the none -TT type, TT- type is the risk factor of the occurrence of IFI. carrying T allele has no significance with the occurrence of IFI.

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